Variable speed and direction power unit



Patented Dec. 1, 1953 UNITED STATES PATET OFFICE VARIABLE SPEED AND DIRECTION POWER UNIT Alex Taub, Washington, D. 0., assignor to Taub Engineering Company, Washington, D. (3., a

corporation of Delaware 5 Claims.

This invention relates to a variable speed and direction power-pack, and more particularly, to a mechanical combination of power units and gearing to provide a selectively reversible power output shaft of infinitely variable speed, and also a constant speed power output shaft.

Heretofore, such devices have been in use wherein an electric motor drives a hydraulic pump which, in turn, drives a reversible hydraulic motor; the whole deriving power from an engine generator set remote from the device.

The present invention makes possible the elimination of electrically driven power units to pro vide operation without a supply of electricity, and would be used, by way of example, for operating weapons independent of each other or of a central power station.

Also, this invention makes possible the direct coupling of an engine to gear units, thereby eliminating power conversion steps and requiring considerably less fuel for storage or in a moving supply which is an extremely important factor in the supply problem for weapons. Moreover, since weapons or special machines may have to be used in extreme cold, the heat of the engine, which is normally wasted, will have many uses.

Other advantages of the invention will be apparent from the following description and accompanying drawing, which is a schematic showing of the power-pack embodying this invention.

Referring now to the drawing, there is shown a power-pack having twin internal combustion engines Ill and I 2, rotating in opposite directions. Gears It and [6 on the output shafts l8 and 20, respectively, of the engines mesh with and drive in a 1-to-1 ratio corresponding gears 22 and 24 that are rotatably mounted on a powerpack output shaft 26. concentrically secured to the opposed faces of the gears 22 and 2d are the opposite bevel gears 28 and 30, respectively, of a differential gear unit 32, having the pinion gears 34 thereof mounted on stub shafts 36 secured radially on the power-pack output shaft 26.

Hence, when the engines It and 12 are rotating at the same speed, the bevel gears 28 and 38 rotate at the same speed, but in opposite directions, so that the pinion gears 34 do not revolve orbitally about the axis of the bevel gears. When the engines I 0 and 12 run at different speeds, however, the pinion gears 34 revolve orbitally and so rotate the power-pack output shaft 26 at a speed proportional to the difference in speed between the two engines, and in a direction dependent upon which engine is running faster. With the l-to-l driving ratio shown, the speed of the power-pack output shaft 26 is one half of the speed difference between the engines, since the torque of the output shaft 26 must equal the sum of the torques of the bevel gears 28 and 38 with a corresponding reduction in speed of such shaft to one half of the difference in speed between the bevel gears.

Hence, by the use of a compensator speed regulator for the twin engines It and 42 for varying their speed equally and oppositely from a predetermined equal speed, the speed of the readily reversible power output shaft 28 may be varied with great precision. Such a compensating speed control is indicated generally at 3B, but it will be e realized that the particular arrangement shown is for illustrative purposes only. In general, there can be used any servo-type control able to vary the speed control of the power units to maintain the relative power unit speeds needed for a certain output speed.

In the embodiment iliustrated, the compensating speed control 38 has a constant speed synchronous electric motor Qt, powered by a source of electrical energy later described, rotating a flat disc 42. Splined to axially ali ned rotatable shafts M and 36, disposed diametrically of the disc 42, are a pair of rollers, 5t and 52 respectively, that bear against the face of the disc on diametrically opposite sides of its axis. Hence, rotation on the disc 42 drives the shafts it and 46 in opposite directions. A rack 54 is mounted for longitudinal slideable movement parallel to shafts t4 and 46. Projecting from the rack 54 are two spaced pairs of ears 55, the ears of each pair straddling a corresponding roller 50 or 52 and closely fitting into circumferential grooves 58 formed in reduced portions of the rollers on opposite sides of their disc-engaging surfaces. Hence, longitudinal movement of the rack 54, by an operating handle {it of a pivoted segmental control gear 6!, shifts the rollers 5i! and 52 equal distances axially along their driven shafts 44 and it. When the rollers are equally spaced from the axis or center of the disc 42, the speeds of the shafts is and 4 5 are equal, but axial shifting of the rollers by the rack 54 will change the shaft speeds equally and oppositely and by an amount proportionate to the movement of the rack.

Each of the two shafts it and 35 drives a bevel gear of a separate difierential gear unit 552 and 54. Since the operation of each of these differential gear units 62 and is identical, a description of the unit 62 will suffice. The shaft M, through appropriate gears 65 and a shaft 68,

drives the bevel gear H3 of the differential unit 62. The other bevel gear 12 of the unit 62 is driven in an opposite direction by the power output shaft l8 of the engine Ill by an appropriate drive train of gears Hi and '56, and shafts is and 38. The drives for the two bevel gears 18 and 12 are arranged so that they are driven at equal speeds in opposite directions when the control handle SE is in neutral position, i. e. the rollers 55 and 52 are equidistant from the axis of the disc 82. The pinion gears 82 of the differential unit s2 are mounted on stub shafts 84 secured to the interior of a rotatable housing 85 journalled on the shafts es and 83. Hence, the housing 88 is stationary when the bevel gears "lo and 72 are rotating at the same speed, but a difierence in speed between the latter causes the housing 85 to rotate.

Such rotational movements of the housing 86 are used to control the speed of the engine H), as by a suitable connection, such as the meshing gears 88, one of which is secured to the housing 2'55, shaft worm 82, follower 94 and lever 96, with the butterfly valve 98 in the intake manifold its of the engine. Thus, for example, when the control handle til is rotated clockwise from a neutral position, the rack s moves to the left, thus speeding up the bevel gear 70 relative to the gear 12 of the differential unit 52. The resulting orbital movement of the pinion gears 32 rotates the housing .85 in a direction to cause the butterfly valve 98 to open more, thus effecting an increase in speed of the engine it. Such speed increase increases the speed of the bevel gear 3'? of the differential unit 52, so that-When the speed of the gear l2 equals that of the gear ill, further rotation of the housing 55 ceases and the butterfly valve 93 is brought to rest in a position corresponding to that of the control handle 5%. Likewise, "movement of the control handle in a counterclockwise direction, decreases the speed of the engine Ill.

The speed of the engine i2 is controlled through the differential gear unit 54 by an associated system of shafts, gearing, and levers identical with those descibed for controlling the speed of engine it. The control handle 59 however, effects equal and opposite control of the speeds of the two engines is and I2, so that when one is slowed down, the other is speeded up a proportionate amount. When the control handle to is in neutral, both engines run at a predetermined equal speed, for example, one half of their maximum speed, and the power pack output shaft is stationary. Movement of the control handle out of neutral position, however, causes the shaft to turn in a direction dependent upon whether the control handle 6!} is right or ieft of its neutral position and at a speed proportionate to the extent of movement of the control handle from its neutral position. Hence, the speed of the .power pack output shaft iniiniteiy variable. The predetermined equal speed of both e gines is pro -set into the convpensator speed control 38, but may be changed by varying the speed of the electric motor fill! or varying the spacing between the rollers 59 and 52 by an extensible rack.

Since a dinerential gear unit is essentially a torque balancing device, the greater torque of the faster of the two engines in and i2 acting through the differential unit 32, tends to speed up the slower of two engines, e. increase its speed above the speed thereof effected by the compensating speed control 38. Additionally, no

torque output can be had from a differential driven in this manner without reaction torque on the slower drive side. Some reaction will be provided by the dragging torque of the slower engine (its friction horsepower). In order to hold down the speed of the slower engine and also, to provide the necessary reaction torque for the faster engine to deliver to the shaft 26 a torque greater than this dragging torque, each engine drives an adjustable torque absorber which may be a loadable hydraulic pump, a loadable electric generator, an adjustable friction brake, or other appropriate means for absorbing or counteracting the speed-accelerating torque imparted to the slower engine through the differential gear unit 32.

For illustrative purposes, such torque absorbers are herein shown as hydraulic pump units Hi2 and 4 B t driven by the power output shafts is and 28 of the engines Iii and i2. Each pump unit has a pump liit receiving liquid from a sump 19-3 and returning liquid to the latter through a conduit having a variable flow restriction iii! therein controlled by a stem H2. Since both pump units 582 and its are controlled in an identical manner by the compensating speed control 38, a description of the control mechanism for the pump unit 32 will suffice for both.

The flow-restriction control stern H2 of the unit #82 has a recess 5M therein. One end of a pivoted lever H6 is received in the recess lit while the other end of the lever has a follower H8 riding in a worm fit on a rotatable shaft I22. Hence, rotation of the shaft 522 in one direction will further restrict the how from the pump Hi5 and increase the torque necessary to drive the latter, 1. e, in another sense, apply a braking or dragging force to the engine shaft 58. Meshing gears i225, one of which is fixed to 'ie housing 85 of the differential gear unit 62, chest rotation of the shaft 122 to vary the flow restriction H9 in accordance with the direction of rotation of the housing 8%. Therefore, this control mechanism for the pump unit it; is so arranged that when the speed of the engine it is at the corresponding speed of the shaft t3, the restriction to flow in the unit P32 is not increased, but when the speed of the engine it is above the corresponding speed of shaft fit, determined by operation of the control handle 68, the consequent rotational movements of the housing 85 of the differential unit S2 act to restrict flow in the unit Hi2 to a degree substantially proportionate to the speed of the engine it above the corresponding speed of shaft (is. In other words; the braking or dragging force applied to the engine iii, 1. e. torque absorption, is respectively increased or decreases substantially in proportion to its speederror above or below the correct speed determined by the compensator. Since the pump unit its is controlled by an identical mechanism connected to the differential gear unit Ed, thegreater torque of the faster engine will not speed u the slower above its correct compensated speed, beo'a so the greater torque is counteracted and balanced by the reaction torque of the slower engine and the reaction torque of the torque absorber driven by the slower engine. Hence, the speed of the powerpack output shaft is correctly governed by the control handle tdof the compensating speed control 38.

The linkages for operating the engine speed controls or throttles and torque absorbers are so coordinated that torque absorption begins as the throttles alternately approach the closed position from neutral. In other words, the flow restrictions IIO offer practically no resistance to flow when both engines are operating at their predetermined equal speed, but act to restrict flow in the unit I02 or I04 in proportion to the speed of the slower engine below the equal speed. Further, a spring or lost motion connection (not shown) is provided in each throttle linkage, in order to absorb or eliminate forces acting on this linkage during the continued movement of the torque absorber linkage with the throttle closed.

The governing effect of the torque absorbers I02 and I04 is supplemented by the action of a constant speed shaft I26, having radial stub shafts I28 mounting the orbital pinion gears I30 of a differential gear unit I32, the bevel gears I34 and I36 of which are rotatably mounted on the shaft I 26. One bevel gear I34 of the unit I 32 has a gear I36 concentrically secured thereto, and driven in a 1-to-1 ratio by a gear I38 fixed on the power output shaft 20 of the engine I2. The other bevel gear I36 of the differential unit I32 has a gear I40 concentrically secured thereto and driven in the same direction as the gear I36 by an idler gear I42, meshing with a gear I 44 mounted on the power output shaft I8 of the engine I0. The gears I40 and I44 are of equal diameter so that the gear I44 drives the gear I40 in a 1-to-1 ratio.

Since the bevel gears I 34 and I36 of the differential gear unit I32 are driven in the same direction, and at the same speed as the power output shafts 20 and I8, respectively, the shaft I26 is rotated by the orbital gears I30 at a speed proportional to the sum of the speeds of the engines I and I2, which sum is constant because of the action of the compensating speed control 38. Therefore, for the driving ratios shown, the shaft I26 is driven at a constant speed equal to one half of the sum of the speeds of the engines I0 and I2.

Driven by the constant speed shaft I26 is an electric generator I46 which supplies power, by conductors I 48, to the synchronous electric motor 40 employed as a time keeper or constant speed reference in the compensator speed control 38. Preferably, a flywheel I50 is mounted on the shaft I26.

The generator I46 and/or the flywheel I50 constitute rotary inertia means that supply an inherent temporary torque reaction for the bevel gears I34 and I36 of the differential unit I32, so that a change in speed of one engine, either an increase or decrease, tends to correspondingly decrease or increase the speed of the other engine. Hence, the constant speed rotary inertia means effects accurate and fast response of the power-pack output shaft 26 to the movements of the speed control handle 60.

It will be realized that various changes may be made in the specific example shown and described for the purpose of disclosing this invention without departing from the principles thereof. Therefore, this invention includes all modi- 6 fications encompassed within the spirit and scope of the following claims:

l. A variable speed and direction power drive comprising: a pair of power units; a diiferential gear unit having opposite gears and an orbital gear with said opposite gears connected to said power units for drive thereby in opposite directions and for power takeoff from said orbital gear; compensator means associated with said power units for changing their speed equally and oppositely from a predetermined equal speed; and a pair of adjustable torque absorbers each driven by one of said power units and both connected to said speed compensator for adjustment thereby to vary the resistance to each power unit in accordance with its speed.

2. A variable speed and direction power drive comprising: a pair of power units; a differential gear unit having opposite gears and an orbital gear with said opposite gears connected to said power units for drive thereby in opposite directions and for power takeoff from said orbital gear; a second differential gear unit having opposite gears and an orbital gear with said opposite gears of said second gear unit connected to said power units for drive thereby in the same direction; inertia means driven by said orbital gear of said second differential gear unit; and speed compensator means associated with said power units for changing their speed equally and oppositely from a predetermined equal speed.

3. A variable speed and direction power drive comprising: a pair of power units; a differential gear unit having opposite gears and an orbital gear with said opposite gears connected to said power units for drive thereby in opposite directions and for power takeoff from said orbital gear; a second differential gear unit having opposite gears and an orbital gear with said second gear unit opposite gears connected to said power units for drive thereby in the same direction; inertia means driven by said orbital gear of said second differential gear unit; speed compensator means associated with said power units for changing their speed equally and oppositely from a predetermined equal speed, and a pair of adjustable torque absorbers each driven by one of said power units and both connected to said speed compensator for adjustment thereby to vary the resistance to each power unit inversely to its speed.

4. The combination defined in claim 2 in which the inertia means comprise an electric generator and a synchronous electric motor powered thereby, the speed compensator means including said motor as a constant speed reference therefor.

5. The combination defined in claim 1 in which the power units are internal combustion engines rotating in opposite directions.

ALEX TAUB.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 695,005 Sponsel Mar. 11, 1902 1,886,975 Profitlich Nov. 8, 1932 2,195,139 Waseige Mar. 26, 1940 2,252,545 Benz Aug. 12, 1941, 

